C6 Rates & Equilibria

Question 1

RPA 5a

Answer 1

20cm3 of 0.4mol/dm3 hydrochloric acid (using 16cm3 water and 4cm3 HCl 2.0mol/dm3 so concentration can be changed later) in boiling tube

rub 3cm magnesium ribbon down with sandpaper and prepare gas syringe with stand and clamp

boiling tube in rack, put the ribbon in the tube, start the stopwatch to measure volume of gas produced in 20 seconds

reset apparatus and use new ribbon each time

rate = cm3/s

Question 2

find rate of reaction on a graph

Answer 2

draw tangent

y2-y1/x2-x1

Question 3

requirements for patricle reaction

Answer 3

activation energy
collision

Question 4

effect of concentration on rate

Answer 4

higher conc = higher rate

higher conc = more particles = closer together = more frequent successful collisions

Question 5

effect of pressure on rate

Answer 5

higher pressure = higher rate

higher pressure = particles closer together = more frequent successful collisions

Question 6

effect of temperature on rate

Answer 6

higher temp = higher rate

higher temp = particles have more Ek and move faster = more frequent collisions

Question 7

SA of solids

Answer 7

higher SA:v = higher rate

higher SA:v = more reactant surface = more frequent collisions

Question 8

Catalyst

Answer 8

less activatione energy required = higher rate

Question 9

RATE IS FAST/SLOW

Answer 9

Most reactant particles in the beginning, vs running out at the end

Question 10

differences in rate graphs by changing factors

Answer 10

steepness and height are NOT connected

steepness = rate of reaction (1/2 vol but 2x conc = same rate = same particle count)
height = reacting quantities (doubles or halves)

Question 11

closed system

Answer 11

no substances can enter or leaved

Question 12

dynamic equilibrium

Answer 12

the forward and reverse reactions are occurring simultaneously and at te same rate

Question 13

DE temp inc

Answer 13

moves to the endothermic side to cool down

Question 14

DE pressure inc

Answer 14

moves to side with less molecules to lower

Question 15

DE concentration inc

Answer 15

moves to side with less molecules

Question 16

le chatelier

Answer 16

the equilibrium strikes back

Question 17

RPA 5b

Answer 17

Sodium thiosulfate 0.2mol/dm3 collected in beaker

(Dilute with water 4:1 to get 0.04mol/dm3 and add more parts at each interval) and put in conical flask on top of piece of paper marked with black X

10cm3 hydrochloric acid constant conc measured and added to flask, start stopwatch immediately

time for turbidity

rate of reaction as 1000/time